On Fri, 29 Jan 2021, at 19:29, Paul Gilmartin wrote:
> On Fri, 29 Jan 2021 19:06:55 +0000, Jeremy Nicoll wrote:
> 
> >On Fri, 29 Jan 2021, at 03:27, David Crayford wrote:
> >    ...
> >Later, I wrote a PF-key driven editor (that is users did not have to
> >remember any commands; everything they did was selected by
> >pressing various PF keys whose labels (and actions) were context
> >sensitive.  That was designed for use by very naive users who did
> >not have (allocated lecture-course) time to learn to use anything
> >complex.
 
> ??? That seems an internal contradiction: it should be easier to
> memorize command names than PF key definitions.

The students concerned had a total of let's say one day (it might 
have been half a day) to learn about the task they had to do, 
learn to use a text editor, learn how to write and test their very
simple program, and feel they'd achieved something.  None of 
them had any knowledge of any kind of computer at the start
of the course.

The system editor was Xedit and it wasn't possible to lock down 
how it worked so that they couldn't tie themselves in a knot.

I was asked to write something that would, like a normal editor
display the contents of the file, allow them to duplicate lines,
delete them, move, copy them, & insert new ones (I think that's
all).  

So in the default view there would be a small number of PF keys
active, each of which if pressed would commence a series of 
prompts depending on what had been pressed.  I can't recall
the fine details, but while someone was, say, moving a line, the
only things they could do were identify the line that was to be 
moved or cancel the process.  Once they'd identified the line,
the next choice allowed only identification of where the line was
to go, or cancel the process.  And so on.

> And "PF keys whose labels (and actions) were context sensitive"
> (extremely modal) is only possible with a very sophisticated
> terminal that can re-label keys depending on context (like
> Mac Pro's touch bar?)  Or was there a key legend on screen?

I'm not sure that anything was "very sophisticated".  The screen
contents was under the total control of the editor program. We
did not have ISPF (too expensive).  Instead the utility that was eg
used to present screens for data entry was used to present the
editor view, and if eg at the foot it said "PF7 Move" then the 
user would be able to press PF7 to initiate a Move process. If
they pressed an unlabelled PF key, nothing would happen.  I'm
fairly sure that as soon as a Move was being done the fields 
that contained lines of data were protected so they couldn't 
change lines while moving others

It was deliberately designed (by the teaching staff) to be far,
far less powerful than Xedit.

-- 
Jeremy Nicoll - my opinions are my own.

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